title: Antibodies to citrullinated α-enolase peptide 1 and clinical and radiological outcomes in rheumatoid arthritis.
abstract: BACKGROUND
  The anticyclic citrullinated peptide 2 (anti-CCP2) assay is a generic test for antibodies to citrullinated proteins, among which there is a subset of about 50% with antibodies to citrullinated enolase peptide 1 (CEP-1). The anti-CEP-1 positive subset is strongly associated with the HLA-DRB1 shared epitope and its interaction with smoking.
  
  
  OBJECTIVE
  To investigate whether anti-CEP-1 antibodies may be helpful in predicting outcome.
  
  
  METHODS
  Anti-CEP-1 and anti-CCP2 antibodies were measured in two prospective cohorts of patients (Karolinska n=272, Norfolk Arthritis Register (NOAR) n=408) with early rheumatoid arthritis (RA). Outcomes measured were C-reactive protein, erythrocyte sedimentation rate, visual analogue scales for pain and global assessment of disease activity, Health Assessment Questionnaire, physician's assessment, swollen and tender joint counts and radiological progression.
  
  
  RESULTS
  Anti-CCP2 antibodies were present in 57% and 50%, and anti-CEP-1 in 27% and 24% of the Karolinska and NOAR cohorts, respectively. Importantly, no statistically significant differences in clinical outcomes were demonstrated between the anti-CEP-1-/CCP2+ and the anti-CEP-1+/CCP2+ subsets in either cohort, or in radiological outcomes in the Karolinska cohort.
  
  
  CONCLUSIONS
  Although antibodies to specific citrullinated proteins may have distinct genetic and environmental risk factors, the similarity in clinical phenotype suggests that they share common pathways in the pathogenesis of joint disease in RA.
authors.affiliation: Kennedy Institute of Rheumatology, Imperial College London, UK. benjamin.fisher@imperial.ac.uk
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Fisher
authors.forename: Darren
authors.initials: D
authors.lastname: Plant
authors.forename: Monica
authors.initials: M
authors.lastname: Brode
authors.forename: Ronald F
authors.initials: RF
authors.lastname: van Vollenhoven
authors.forename: Linda
authors.initials: L
authors.lastname: Mathsson
authors.forename: Deborah
authors.initials: D
authors.lastname: Symmons
authors.forename: Karin
authors.initials: K
authors.lastname: Lundberg
authors.forename: Johan
authors.initials: J
authors.lastname: Rönnelid
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Venables
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D014408:Biomarkers, Tumor / Q000276:immunology*; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000276:immunology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology; D010751:Phosphopyruvate Hydratase / Q000276:immunology*; D011379:Prognosis; D011446:Prospective Studies; D011859:Radiography; D012720:Severity of Illness Index; D025521:Tumor Suppressor Proteins / Q000276:immunology*
chemical_list: D018501:Antirheumatic Agents; D001323:Autoantibodies; D015415:Biomarkers; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D010456:Peptides, Cyclic; D025521:Tumor Suppressor Proteins; C487763:cyclic citrullinated peptide; D002097:C-Reactive Protein; C095157:ENO1 protein, human; D010751:Phosphopyruvate Hydratase